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M25 Universal troubles - need advice

Aug 1, 2020
5
Catalina C30 Midland
Hello,
I have a 1983 Catalina 30 with M25 Universal diesel. Earlier in the season we ran out of oil, alarm came on and we shut the engine down as soon as we noticed the alarm. Got back to port, which is a long story, and found that there were two gaskets on the oil filter; not recommended. Anyway, changed the oil filter, put in new oil, new impeller, new fuel filters and went back out. No issues until we went to anchor. Put the rpms to idle to anchor and alarm came back on. Checked oil levels and it was fine, water was coming out the back and temp seemed fine. Since then the engine has run fine at cruising speed, with no alarms, and will idle cold at the dock with no alarms either. However, every time we run the motor to our destination (usually about two hours of run time), go to anchor or when we come back to the dock (again after two hours of run time) we get an alarm at idle rpms. Right when we need it the most. Any ideas what could be causing the alarm to come on? Please don't say oil pump...maybe a sensor? maybe the alarm panel?...any help would be greatly appreciated.
 

MitchM

.
Jan 20, 2005
858
Nauticat 321 pilothouse 32 Erie PA
Might be worth replacing your oil pressure sending unit. If the wire has deteriorated it may be throwing a faulty signal.
 
Feb 26, 2004
21,141
Catalina 34 224 Maple Bay, BC, Canada
What is your idle rpm? If too low, it could be affecting the oil pressure, making it just low enough to trigger the alarm.
 
Jan 4, 2006
2,964
Hunter 310 West Vancouver, B.C.
Anyway, changed the oil filter, put in new oil, new impeller, new fuel filters and went back out.
What is this new impeller you refer to ?

Might be worth replacing your oil pressure sending unit
IMO I would go with this first, based on a gradient of working from cheapest $ to most expensive $$$ repair ............................ unless @Stu Jackson is on to something with RPM.
 
May 29, 2018
194
Canel 25 foot Shoigama, japan
I wonder why the original poster said this, "Please don't say oil pump...maybe a sensor? maybe the alarm panel?...any help would be greatly appreciated. "

He/she didn't mention that they had been dealt with.

Gary
 
Aug 1, 2020
5
Catalina C30 Midland
What is this new impeller you refer to ?



IMO I would go with this first, based on a gradient of working from cheapest $ to most expensive $$$ repair ............................ unless @Stu Jackson is on to something with RPM.
It is a water impeller. Oberdorfer. I think this will be my attack angle as well.
Thanks,
 
Aug 1, 2020
5
Catalina C30 Midland
I wonder why the original poster said this, "Please don't say oil pump...maybe a sensor? maybe the alarm panel?...any help would be greatly appreciated. "

He/she didn't mention that they had been dealt with.

Gary
Hi,
I don't want it to be the oil pump (it probably is the oil pump though) because it requires lifting the motor out of the boat! $$$.
 
Jan 4, 2006
2,964
Hunter 310 West Vancouver, B.C.
It is a water impeller. Oberdorfer. I think this will be my attack angle as well.
I would suggest sticking to the oil distribution system. The water pump has nothing to do with the oil pressure.

Start with the suggestions listed above and make a list, working from simple ($) to complex ($$$). I've got two dimes, a nickel, and ball of lint that says the problem's in the alarm system :biggrin:.
 
May 24, 2004
6,343
CC 30 South Florida
Running an engine with low oil presure usually will first reflect on noises in the valve train. Prompt shutdown after buzzer alarm will usually leave no ill effects. A faulty sensor will usually have the alarm going at all RPM. My money is on low idle speed. Bring it up to about 850 RPM.
 
May 29, 2018
194
Canel 25 foot Shoigama, japan
You don't know what the oil pressure is.
You need to know what the oil pressure is before you go to any next step.
An oil pressure gauge will tell you much more than I or anyone else on here can.

gary
 
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jviss

.
Feb 5, 2004
4,580
Tartan 3800 Westport, MA
If you have a low oil pressure problem, you will be lucky if it's just the pump. One cause of low oil pressure is worn-out main bearings. This could get expensive.

Install an oil pressure gauge, is my recommendation, and then see what's really going on.
 
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RitSim

.
Jan 29, 2018
135
Beneteau 411 Branford
If you are handy with tools and engines, this is rebuildable. I took off the galley counter and this exposed the entire engine - gave lots of room. I chose to lighten the engine by doing most of the dismantling on board. The block/pistons/crankshaft brought it down to a weight I could get off the boat by using the boom. I did all my rebuilding at home and got the yard to just drop it in. Got my parts from an aftermarket place in NJ - Kumar Bros. The manuals you need are on one of the Catalina sites C30 or C34 or PM me.

I had a cracked head and water leaked into the middle cylinder damaging the liner. Had it bored and put on a new head. While I did get the parts I needed from the place referenced above, You still have to be vigilant - they sent me the wrong head - it bolted on but I couldn't rotate the engine full rotation by hand and one of the o-rings in their kit was too big- I used the old one.

I agree with taking the oil pressure. I think you will find that the threads to the oil port are not national pipe thread - don't force anything
 
May 24, 2004
6,343
CC 30 South Florida
With what grade of oil did you replace it with? With a 30+ year old engine even with average hours the oil grade should be at least 15W-40 and it would not hurt to add a quality oil additive. It will help, both compression and oil pressure.
 

cjm1

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Jul 10, 2013
36
custom Herreshoff 33 sloop Lake Charlevoix
That is how I got a Universal 5432 with 50 hours on it cheap ($600.00). The wrong oil filter was put on for the first oil change and it blew off just out side the harbor. The yard put proper filter on and filled the oil and could only get 20 Lbs of oil pressure (normal 60 lbs). The new owner got a new engine and I had a project. A real oil pressure gauge will tell you everything and easy to hook up. The engine required 3 main bearings replaced and a bit off crank turning (done by a Kubota tractor company). It now has 900 hours and never a problem.
 

MitchM

.
Jan 20, 2005
858
Nauticat 321 pilothouse 32 Erie PA
let's start from scratch: get a mirror a roll of papertowels and a flashlite. wipe your bilge clean under yr cold engine particularly near the oil feed lines and oil filter. check the oil level cold on yr dipstick before startup--is it OK ? (you'll also need to check dipstick again after your 2 hr run and w engine cooled down --you are looking for any loss of oil ?) check your oil feed line from filter into engine before you start the engine by running a kleenex along the line (or pipe) and looking for oil , any drips or seepage along the line or pipe? any oil drips in the bilge? now check oil filter gasket-- positioned securely w/ good seal? ( make sure someone didn't accidentally install 2 gaskets by forgetting to remove the old one when they changed the oil filter which can lead to a leak at the gaskets when the engine gets hot and will also show as a loss of oil on the dipstick) (, and yes i have seen this happen..) now check around where oil pressure sender unit screws into the block (usually yellow wire if it's standard color protocol): any leaks or seepage visible? check OPressure sender wire- use a flashlite, can you see any cracks or deterioration ? same for the oil temperature alarm unit . now set idle rpm higher at 900 not 650 ish . sratrt the engine -- does OP increase to suitable levels at the higher idle? listen to yr running engine w stethoscope-- hear any weird bearing noises ? as the engine rotates faster the oil pump speed and pressure increases. as a wire ages its resistance increases. old wires are known to thrown weird electrical signals, especially when they get hot. so i am back to : the oil pressure sending unit or the oil temp alarm.
on my yanmar 3JH4E i had an overtemp alarm -- it was caused by loss of oil due to a tiny separation in the oil reservoir suppply line .yanmar's stupid design necked this rubber hose down about an 8th of an inch in diameter-- the hose had developed a tiny pinhole leak as it entered the bottom oil reservoir ...a leak detectable only after the engine was running at normal speed for a 1/2 hour or so. oil started appearing as a tiny drip under the feed line where the diameter necked down. ( and it was 3 weeks to get the replacement line ..)
 
Feb 26, 2004
21,141
Catalina 34 224 Maple Bay, BC, Canada
Mitch, that's a fascinating and helpful post about how to do really good forensics. There are, however, significant differences between Yanmar engines and the OP's M25.